.epsilon.-Caprolactam has been produced mainly by converting cyclohexanone to an oxime, and subjecting the formed cyclohexanone oxime to a Beckmann rearrangement. The cyclohexanone oxime is usually produced by reacting cyclohexanone with hydroxylamine.
Heretofore, for the production of cyclohexanone which is useful for producing .epsilon.-caprolactam, it has been most common to employ a method which comprises oxidizing cyclohexane with molecular oxygen to obtain a mixture of cyclohexanol and cyclohexanone, separating cyclohexanol and cyclohexanone by distillation and converting the separated cyclohexanol to cyclohexanone by a dehydrogenation reaction, as an industrially practiced method. Also known is a method wherein phenol is subjected to hydrogenation and dehydrogenation to obtain cyclohexanone.
On the other hand, an attention has been drawn in recent years to a method of hydrating cyclohexene in the presence of a solid catalyst, particularly a zeolite catalyst, as a method for producing cyclohexanol on an industrial scale. Many reports have been made on such a method since about 1965, but a production on an industrial scale has only recently been realized (Chemical Economy, 1993 March issue, p. 40-45).